Scanning pulsed profilometer

摘要

An optical profilometer measures the surface profile of a sample by using a scanning autocorrelator and relating the autocorrelation signals at the scanning frequency, f, and twice the scanning frequency, 2f, to the path length changes in one of the arms. The amplitude of the signal at the scanning frequency is used to control the average position of the scanned arm of the autocorrelator, thereby further extending the linear range of the profilometer. The scanning rate of the autocorrelator is set to be much faster than the mechanical noise so that mechanical fluctuations of the sample produce slowly varying fluctuations in the sample scans.